It was the other way around. The keyboardist Einar did the cleans and the guitarist Oystein did the growls (i.e. - "Your God is not my God", etc.)

This was the best performance I have ever seen at the 5 ProgPowers I've been too. Hands down. And quite possibly the best performance I've seen ever in my nearly 30 years of going to shows. It was THAT amazing.